The present invention relates to pedal output conversion apparatus and methods for outputting a control value (tone control information) pertaining to tone control, such as tone volume value control, in response to operation of a pedal of a pedal operator unit, and more particularly to a technique for controlling a tone with unevenness or variation in a control value, which may occur due to individual differences, aging, etc. of the pedal operator unit, appropriately compensated for.
Heretofore, in electronic keyboard instruments, such as electronic pianos, a pedal operator unit (i.e., pedal-type operating member unit) is popularly employed as a controller for, for example, controlling an attenuation amount of a tone volume or lowering a tone volume and softening a tone color. In some cases, the pedal operator unit is used to impart a continuous pitch-bend effect to a tone as a special effect not achievable by an acoustic piano. One example of such apparatus is disclosed in Japanese Patent Application Laid-open Publication No. HEI-07-036460 (hereinafter referred to as “the patent literature”).
In the conventionally-known apparatus as disclosed in the patent literature, to further approximate the operational feeling of a natural musical instrument, such as a piano, one or more pedals P of the pedal operator unit U are supported by respective springs B, as shown in FIG. 5. Thus, as a user reduces his or her depressing force on any one of the pedals P, the pedal P resiliently returns to a predetermined position, defined by a stopper T (fixed to an outer casing or the like and having a shock absorbing member like felt F), by a biasing force of the spring B that acts in response to user's depression of the pedal P. In other words, the stopper T determines an upper limit of the movable range of the pedal P, while the spring B determines a lower limit of the movable range of the pedal P. An angular position at which the pedal P is located within a movable range of the pedal P (this angle will hereinafter be referred to as “depressed angle” or “depressed position” for convenience of description) can be taken out as an analog value corresponding to a resistance value of a variable resistor K. Tone control information representing a digital control value, for example, in a numerical value range of 0-255 is determined on the basis of the taken-out analog value (i.e., output value in the movable range). Such arrangements allow a tone to be controlled in a continuous or multi-step fashion in response to user's operation of the pedal.
However, with the conventionally-known apparatus, the resistance value (output value) of the variable resistor K responsive to the depressed angle of the pedal P and hence the control value can undesirable vary because individual differences of the pedal operator unit U may result from mounted conditions of a multiplicity of component parts, such as the pedals P, variable resistors K, stoppers T, springs B, etc., constituting the pedal operator unit U and because aging of the component parts, such as deterioration of the felts F, weakening of the springs B and deviation of relative mounted positions movable of the individual component parts. Namely, due to the individual differences, aging, etc, of the pedal operator unit U, the control value responsive to the depressed angle of the pedal P would undesirably vary or become uneven even for the same depressed amount, in which case it would be extremely difficult for a user (human player) to perform appropriate tone control by depressing any desired one of the pedals P with an always constant operational feeling (depressed amount) without being adversely influenced by individual differences, aging etc. of the pedal operator unit U.
Thus, in order to prevent variation or unevenness from occurring in the control values due to individual differences, aging, etc. of the pedal operator unit U, the conventionally-known apparatus is constructed to appropriately adjust an effective range within which to output control values (i.e., effective control value outputting range) without being influenced by the individual differences, aging etc. of the pedal operator unit U, by previously providing, in the movable range of the pedal P, play or idle regions as shown in FIG. 5 where output of the control value is inhibited, The provision of such idle regions may be advantageous in that the wider the idle regions, the wider the apparatus can cope with the individual differences, aging, etc. of the pedal operator unit U; however, if the idle regions are too wide, then there would be presented the problem that the effective pedal operating range is considerably limited so that response to user's pedal depressing operation is sacrificed and thus a direct operational feeling is lost, which would make it difficult for the user to operate the pedal.
Another conceivable approach may be to assemble a pedal operator unit U using component parts formed of heavy-duty members or to design a heavy-duty pedal operator unit U capable of enduring aging. However, such an approach would undesirably increase manufacturing cost of the pedal operator unit U.
Further, the prior art apparatus can not quickly deal with a situation where there has occurred an inconvenience that supposed control values can not be output during a performance due to individual differences, aging, etc. of the pedal operator unit U.